In U.S. Pat. No. 4,927,991 (Wendt), assigned to The Pillsbury Company, the disclosure of which is incorporated herein by reference, there is described a novel form of food package for a microwave oven which has a microwave-reflective grid in combination with a microwave susceptor. This combination provides a useful arrangement in the microwave cooking of foodstuffs for consumption, by controlling surface heating and microwave transmittance to the foodstuff to achieve a more uniformly heated product.
However, in each of the embodiments described in U.S. Pat. No. 4,927,991, the microwave susceptor, that is, the element of the structure which generates thermal energy when exposed to microwave radiation, takes the form of a thin metal film, usually aluminum, supported on a polymeric substrate layer.
When the arrangement of susceptor and grid is incorporated into a packaging structure in this prior art, multiple layers are required, typically the susceptor-polymeric film combination adhesively bonded by laminating adhesive to a paper or paperboard layer, which usually forms part of the package, the grid, usually formed of aluminum foil, adhesively bonded by laminating adhesive to the susceptor-polymeric film combination on the opposite side from the paper or paperboard layer, and a polymeric film layer adhesively bonded by laminating adhesive to the grid to avoid the foodstuff contacting the grid directly.